Isolation, Incidence and Molecular Characterization of Drug-resistant Escherichia coli of Goat Milk

Background: Goat milk is recognized for its high nutritive profile. The practise of antimicrobials in feeding of animals produces resistance in bacteria. Therefore, the present study was proposed to study the incidence of drug-resistant E. coli from raw goat milk samples and investigate the genes responsible for the resistance.

Methods: A total of 250 raw milk samples were obtained from different farms of Taif province, Saudi Arabia. Collected samples were cultured on MacConkey agar. Morphological and biochemical tests were achieved for the identification of isolates. Antimicrobial resistance pattern of E. coli was estimated by the disk diffusion method. The resistance genes tet(A) and tet(B), ere(A), aadA1, blaSHV, aac(3)-IV, sul1, catA1 and cmlA, were examined by PCR.

Results: Results of the present study showed that out of the 250 samples examined, 100 (40%) were found to be infected with E. coli. Antimicrobial resistance profile evaluated showed a higher resistance against ceftriaxone (90 %) and ticarcillin (86%), followed by amikacin and cefotaxime (87%), and augmentin and penicillin (85%). Lower percentage was observed for gentamicin (58%), ampicillin (66%), bacitracin (75%) and imipenem (32%). Furthermore, multi-drug resistance was observed in most of the isolates. Among E. coli isolates, 86% gave positive amplicons for the blaSHV gene followed by tet(A) and tet(B) genes (85%).

Conclusion: The results suggested a probability of possible public health risk of multi-drug resistance of E. coli strains collecting from raw goat milk samples. Consequently, appropriate handling of goat milk processing is significant to prevent E. coli infection.